The present invention relates to implants to be situated in the vas deferentia of adult male animals for the purpose of controlling conception.
Implants of this type are generally know. For example, such implants are capable of blocking the flow of fluid through a vas deferens in order to prevent conception, and of course there are known implants which can be placed in a position which will again permit fluid to flow through a vas deferens to that it is possible in this way to achieve reversible contraception, with the capability of conceiving being restored when desired.
However, the problem with implants of the above general type is that they operate, when preventing conception, by completely blocking the flow of fluid through a vas deferens. Such complete blockage of the flow of fluid is highly undesirable. Thus, the preventing of sperm flow is undesirably accompanied by preventing of flow of the fluid which carries the sperm, and thus beneficial effects resulting from the flow of this latter fluid are prevented with conventional implants as referred to above. The fluid which flows through the vas deferens serves not only to carry sperm but also to perform other functions such as supplying certain hormones and enzymes to the body, maintaining the lumen of the vas deferens in an open condition enabling fluid to flow properly therethrough, and avoiding undesirable build-up of pressure. Moreover, with complete blockage of flow through the vas deferens there is a tendency for the latter to close upon itself downstream of the implant, so that when flow is restored with conventional implants there is still difficulty in achieving reliable flow of fluid through the vas deferens, particularly if the latter has been completely closed over a long period of time.